Left: ESPRESSO data (blue dots) and their linear trend (green line). Middle and right columns: GLS periodograms of the original data and data corrected for the linear trend. The vertical red line stands for the orbital period of the transiting planet GJ7 b, while the pink band indicates the most likely rotation period of the parent star. The 0.1%, 5%, and 10% FAP levels are plotted with horizontal orange lines.